An agricultural harvester, e.g., a plant cutting machine, such as, but not limited to, a combine or a windrower, generally includes a header operable for severing and collecting plant or crop material as the harvester is driven over a crop field. The header has a plant cutting mechanism for severing the plants or crop, such as an elongate sickle mechanism that reciprocates sidewardly relative to a non-reciprocating guard structure or a row unit with gathering chains and deck plates. The header further includes one or more draper belts and/or augers for feeding the cut plants or crop towards a feederhouse located centrally of the header.
To facilitate cutting crop, the header also includes a header height control system. Typical header height control systems have a combination of flex arms and feelers operatively connected to a rotatable control shaft. The flex arms are connected to the cutting mechanism and pivot upwardly as the harvester travels over an uneven terrain so as to enable the cutting mechanism to track the ground. The feelers slidably engage the flex arms and, as the flex arms pivot, rotate the rotatable control shaft. However, this arrangement of feelers, flex arms and control shaft require a specific lockout method, a specific downstop and a specific feeler-flex arm sliding profile, which subjects the flex arm to significant amounts of stress.